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  • 1
    Keywords: SIMULATIONS ; Germany ; POPULATION ; GENE ; SAMPLE ; IMPACT ; SIMULATION ; ASSOCIATION ; polymorphism ; single nucleotide polymorphism ; SUSCEPTIBILITY ; FREQUENCIES ; PERFORMANCE ; NUMBER ; genetics ; SNP ; GENOTYPES ; MEASUREMENT ERROR ; genotyping ; UNCERTAINTY ; sensitivity ; SNPs ; methods ; GENOTYPE ; HAPLOTYPE ; HAPLOTYPES ; TESTS ; TRAITS ; LINKAGE PHASE ; genetic association ; Genetic ; MISCLASSIFICATION ; PROBABILITIES ; single nucleotide ; association studies ; genotyping error
    Abstract: P〉Haplotypes are an important concept for genetic association studies, but involve uncertainty due to statistical reconstruction from single nucleotide polymorphism (SNP) genotypes and genotype error. We developed a re-sampling approach to quantify haplotype misclassification probabilities and implemented the MC-SIMEX approach to tackle this as a 3 x 3 misclassification problem. Using a previously published approach as a benchmark for comparison, we evaluated the performance of our approach by simulations and exemplified it on real data from 15 SNPs of the APM1 gene. Misclassification due to reconstruction error was small for most, but notable for some, especially rarer haplotypes. Genotype error added misclassification to all haplotypes resulting in a non-negligible drop in sensitivity. In our real data example, the bias of association estimates due to reconstruction error alone reached -48.2% for a 1% genotype error, indicating that haplotype misclassification should not be ignored if high genotype error can be expected. Our 3 x 3 misclassification view of haplotype error adds a novel perspective to currently used methods based on genotype intensities and expected number of haplotype copies. Our findings give a sense of the impact of haplotype error under realistic scenarios and underscore the importance of high-quality genotyping, in which case the bias in haplotype association estimates is negligible
    Type of Publication: Journal article published
    PubMed ID: 20649529
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  • 2
    Keywords: Germany ; MODEL ; DISEASE ; GENE ; SAMPLE ; IMPACT ; ASSOCIATION ; FREQUENCIES ; PERFORMANCE ; genetics ; RATES ; REPLICATION ; UNCERTAINTY ; transmission/disequilibrium test ; TESTS ; ERROR ; HARDY-WEINBERG EQUILIBRIUM ; ROBUST ; CONTROL GENETIC ASSOCIATION ; MISCLASSIFICATION ; TAGGING SNP SELECTION
    Abstract: Background: We investigated the influence of genotyping errors on the type I error rate and empirical power of two haplotype based association methods applied to candidate regions. We compared the performance of the Mantel Statistic Using Haplotype Sharing and the haplotype frequency based score test with that of the Armitage trend test. Our study is based on 1000 replication of simulated case-control data settings with 500 cases and 500 controls, respectively. One of the examined markers was set to be the disease locus with a simulated odds ratio of 3. Differential and non-differential genotyping errors were introduced following a misclassification model with varying mean error rates per locus in the range of 0.2% to 15.6%. Results: We found that the type I error rate of all three test statistics hold the nominal significance level in the presence of nondifferential genotyping errors and low error rates. For high and differential error rates, the type I error rate of all three test statistics was inflated, even when genetic markers not in Hardy-Weinberg Equilibrium were removed. The empirical power of all three association test statistics remained high at around 89% to 94% when genotyping error rates were low, but decreased to 48% to 80% for high and nondifferential genotyping error rates. Conclusion: Currently realistic genotyping error rates for candidate gene analysis (mean error rate per locus of 0.2%) pose no significant problem for the type I error rate as well as the power of all three investigated test statistics
    Type of Publication: Journal article published
    PubMed ID: 19178712
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